Last weekend, hundreds of passengers with firm bookings on Richard Branson's European airline were refused seats aboard flights between London and the Belgian capital. For a moment in the check-in queue at Heathrow last Saturday morning, I thought I was about to get an accelerated journey. "We have a flight leaving in 15 minutes. Would you like to take it?"

But this turned out to be a case of Ca Plane Pas Toi. The official was actually talking to the lady next to me. Virgin Express staff were combing the queue identifying passengers planning to connect at the Belgian capital to other destinations, and whisking them away to the first available plane. But, the official explained, "If you're only travelling to Brussels, you won't be allowed to check in for the 8.30am flight. We'll give you a ticket for a Eurostar train which will get you to Brussels at four this afternoon."

The company that calls itself "Europe's most innovative airline" was proposing the innovation of making air passengers travel by bus to Waterloo, and by rail from there. The reason, says the company, is a shortage of capacity.

Virgin Express has expanded rapidly this summer, and now offers 16 flights a day from London to Brussels. The trouble seems to be that the airline has taken rather too many bookings for the available seats. According to Virgin Express, the problem was caused by an elderly Lockheed TriStar aircraft that the airline had chartered in but had proved unreliable. Instead, smaller planes were being used, so there simply weren't enough seats to go round.

The flight I was booked on was to be operated by a small propeller plane, the Fokker 50, which has about one-sixth the capacity of a TriStar. (Planespotters like me are rather bemused about this turn of aeronautical events, since Virgin Express prides itself on a fleet comprising exclusively nice new Boeing 737s.)

Whatever the airline's problems with wonky planes, from the paying punter's point of view this was a straight case of overbooking: the flight was leaving, but without a lot of people who had paid a lot of money to travel on it - and to reach the airport at an unearthly hour.

Leana Hayter, who was also refused boarding, had left her home in Northampton at 4am. She was facing the prospect of getting to her destination 10 hours late. "When I arrived at 6am, I saw people thronging about and thought there must be trouble," she told me. "I'm surprised this can happen on Virgin."

When airlines overbook, they pay compensation. I asked the official what my entitlement was under European Union rules; the EU sets down minimum payments for passengers delayed due to overbooking. "We're a non-Iata carrier [ie not a member of the International Air Transport Association]," he said, "So we're not bound by those rules."

Instead of cash, passengers were handed a letter from Jim Swigart, president of Virgin Express, setting out the compensation for what he called "your inconvenience as well as the additional expenses or time lost that you might have incurred".

The letter promised a free flight to Brussels and back - except the flight isn't free, because passengers have to pay pounds 25 in tax for the privilege, and the offer is hedged with restrictions, such as having to book at least a week in advance, and travel within the next four months.

Passengers who decided instead to abandon their journey were denied even this compensation - instead, Virgin Express offered merely a refund of the money you paid. To add insult to inconvenience, there were no instant refunds, so travellers who may have paid for their tickets weeks in advance are having to wait still longer to get the money back. Faced with the prospect of spending most of the day getting to Brussels, I rebooked instead on the 6.50am flight on Sunday.

Next morning I received a boarding card rather than a rebuff, and even got as far as the departure gate. But because of what was described as "staff shortage", the flight was delayed first by an hour, then indefinitely.

After an hour or so, the departure gate got even livelier when an entire 757-load of passengers and crew turned up expecting to board a BA flight to Copenhagen; Virgin Express had outstayed its welcome at the gate.

The delay extended to the point where the passengers would not reach central Brussels until lunch time. By this time my intended long weekend in Belgium was turning into a day trip. So I abandoned the trip, musing that the slogan of Virgin Express ("Your right to fly for less") could usefully be amended by deleting the word "for".

ANOTHER SLOGAN that caused a kerfuffle: "The next time you find yourself in one of our departure lounges about to board one of our flights, better make it an espresso".

British Airways used this line to publicise its Shuttle flights. But a passenger complained that the ad was inaccurate because he found flights between Manchester and London were frequently delayed or cancelled. The Advertising Standards Authority rejected the complaint, but in the process BA revealed its punctuality record: one in eight flights fails to depart within 15 minutes of the scheduled departure time - even poorer than trouble- prone Virgin Trains.

By the way, here is the sympathetic response you can expect on telling a pal that you've been bumped from a Virgin Express plane: "Gosh, that sounds uncomfortable," said my friend Sue. "I hope not from too great a height."

THE LONG-HAUL branch of the Virgin empire is rather more generous when offloading passengers. Suzy Dietrich of London checked in at Heathrow for her Virgin Atlantic flight to Johannesburg. "Would you mind flying BA instead?", she was asked. She didn't - particularly when told the only inconvenience was a 45-minute delay, and the reward was a free flight to South Africa and back.

"YOU REFER to passengers being 'strapped into an aircraft seat' ", writes John S Smith of Hoverspeed, whose flagship (or is it a flagplane?) I described last week.

"Whilst the hovercraft cabin is more akin to an airline than a ferry, we certainly do not strap passengers into their seats. Although passengers remain seated during the 35-minute crossing, they are certainly not restrained from moving."

Mr Smith also rejects my suggestion that the abolition of duty-free, which comes into effect on 1 July next year, could threaten the future of the craft. "We plan to refurbish them next year, and to operate the hovercraft well into the next Millennium, continuing the tradition of the fastest Channel crossings."